This invention relates to the conversion of energy from fluid streams, for example, winds and ocean currents, and particularly to the use of bluff bodies disposed in such streams for capturing energy by the shedding of vortices from the bodies.
The use of bluff bodies for interacting with fluid streams for capturing energy there from is known. In U.S. Pat. No. 6,424,079, “Energy Harvesting Eel”, for example, a bluff body in the form of a flat plate is placed at 90 degrees to the oncoming stream of water resulting in the generation of vortices at the plate edges. The vortices travel downstream of the plate to interact with a membrane of a piezoelectric power generator. The oscillating series of vortices—termed a von Karman vortex street—produces unsteady pressure variations against the piezoelectric generator in the form of a traveling wave. This unsteady traveling pressure wave causes the membrane to deform and vibrate. The deformation of the membrane generates electrical energy which is harvested with appropriate control electronics.
The present invention makes use of bluff of bodies in a different manner.